Class for manage users groups - symfony

Question

I'm creating a class to manage user groups. A group can contain either users or groups of users
I wonder if there is already a symfony class to implement that handle such relationships.
The best way that occurred to me is something like this:
class Group
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="name", type="string", length=255)
*/
private $name;
/**
* #ORM\ManyToOne(targetEntity="User")
* #ORM\JoinColumn(name="coordinator_id", referencedColumnName="id", nullable=false)
*/
private $coordinator;
/**
* #ORM\ManyToOne(targetEntity="Group")
* #ORM\JoinColumn(name="parent_id", referencedColumnName="id", nullable=true)
*/
private $parent;
/**
* #ORM\ManyToMany(targetEntity="User", inversedBy="users")
* #ORM\JoinTable(name="groups_users")
*/
private $users;
}

Answer 1

There is currently ( as of 2013-06-16 ) no bundle available which directly provides this special implementation.
FOSUserBundle introduces groups for roles ... but the implementation is pretty basic and needs manual hands-on to get it working fully. Maybe it's something you could look into for inspiration though.
Otherwise your approach looks okay to me for this special use-case.
You might be able to improve by using nested sets with Gedmo's Tree doctrine extension to handle the group-nesting.